Monthly Archives: April 2008

Digging Deeper Into Population Change By County Using ArcGlobe

Recently, we have been examining different GIS tools useful for studying population change over time. We began with two-dimensional analysis using ArcExplorer Java Edition for Education (AEJEE), followed by 3D analysis using ArcScene. Let’s turn our attention to another 3D tool called ArcGlobe.

ArcGlobe allows for the viewing of large amounts of GIS data on a globe surface, from local to planetary scale. ArcGlobe supports display and query of raster data, geoprocessing, and geodatabases. It ships with a comprehensive set of imagery on DVD, including planetary elevation data.

ArcGlobe is a part of the 3D Analyst extension. To access ArcGlobe, engage the 3D Analyst extension, turn on the 3D Analyst toolbar, and select the ArcGlobe tool. ArcGlobe opens with a default view of the planet, as follows:

I added my data layer showing 1900 to 2000 population by county to this default globe. I then symbolized the layer by the percent change over a 10-year period, from 1990 to 2000, as quantile. I made certain that one of the break points was 0, so that I could quickly determine which counties lost population during that time period, and which counties gained population. I then accessed the “Globe Extrusion” tab and set the value represented by the counties when they turned into 3D towers, as follows:

“PERCENT” represents the percentage change from 1990 to 2000, but note that it will be extruded above the surface of the Earth in meters. If a county increased by 22%, it would be difficult to see at only 22 meters high. I therefore multiplied it by 10,000, so that this county will tower 22,000 meters high.

After applying, I’m ready to analyze from all angles in 3D:

The advantage of ArcGlobe is that it looks and acts like virtual globe software, but is much faster because the data does not stream from the Internet, but resides and can be cached on the local computer.

ArcGlobe is a fast and easy way of helping students understand change over time in 3D.

- Joseph Kerski, ESRI Education Manager

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Exploring Fire in AEJEE

The approach of summer marks the start of fire season, and there’s an easy way to explore the situation quickly using ArcExplorer Java Edition for Education (AEJEE), ESRI’s free, downloadable, dual platform (Win/MacOSX), lightweight GIS tool. All you need to do is open an AEJEE window and add the “ESRI_MODIS” layer from the Geography Network.

The MODIS layer comes in with indicators of fires from the last day, last week, and this year. It can be a sobering vision, and such impact is necessary for people to fathom the expanding impact of humans on the environment, and the ways in which geography matters.

- Charlie Fitzpatrick, ESRI Education Manager

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Exploring a Midwest Earthquake Zone with ArcGIS Explorer: Part IV

A multi-day blog: Part 1 | Part 2 | Part 3 |
Part 4

I was still curious about the occurrence and geographic spread of earthquake events in the region and along my “line of five.” I likewise noted that the April 18 quake event was reported to be part of the Wabash Valley Seismic Zone though proximate to the New Madrid area. I went back to the earthquake search function at USGS. I grabbed new sets of records from two databases—historic (1534-1986) and recent (1973-present)—for an area bounded by 39N, 34N, 86W, and 92W. I added these point files to my project.

Both the historic (1115 records) and the recent (320) events presented a definite “zigzag” pattern in the New Madrid area. However, the remaining epicenters seemed more scattershot with no discernible pattern…except it is very clear that generally fewer quakes have happened to the southeast. Here is the map showing events from 1973 to 2008 in the area of interest. (NOTE: I also did some Table of Contents cleanup—relabeling and reorganizing my results layers. I also added a link to the City of New Madrid, Missouri Web site.)

So where is the Wabash Valley Seismic Zone and does the seemingly random spread of earthquakes in Southern Illinois associate with any underlying fault zones?

I did a quick Web search on “Wabash Valley Seismic Zone” and found a great map graphic of it and its near south cousin displaying that Wabash events seem to be less “patterned.” Using the “Create Notes” task I added a “ghosted” place marker. I named it, “Midcontinent Danger Zones” and added the map graphic Web address to the note.

Lastly, I searched the Illinois State Geological Survey’s GIS data holdings. This led me to fault data which I downloaded and added (purple lines) to my growing ArcGIS Explorer project. While not all earthquakes in the Wabash region “connect” to the fault lines, some do, and the geographic limits of ISGS data suggest that Indiana fault line data would make a good future addition.

The last project modifications are visible below.

Well, what started as an interest in looking for connections between several Midwestern earthquake events mushroomed into a broader investigation…and many questions. One of the exciting things is that using ArcGIS Explorer provided me a fast way of adding new GIS and multimedia content to the growing exploration. Hopefully it’s offered you a compelling geographic study and a better sense of what you can do with ArcGIS Explorer.

Be sure to see the ArcGIS Explorer blog for another study on the April 18 earthquake in Southern Illinois.

- George Dailey, ESRI Education Manager

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Exploring a Midwest Earthquake Zone with ArcGIS Explorer: Part III

A multi-day blog: Part 1 | Part 2 | Part 3 |
Part 4

Exploring the USGS site further, I found a series of National Seismic Hazard Maps for the country and the region. The images helped me remember that there is a seismic hazards map layer available for free download at the USGS National Atlas. After a needed projection tweak that I accomplished with ArcView 9.2, I added the downloaded hazards layer as a local shapefile to ArcGIS Explorer. Since the hazards layer is a series of polygons, I decided to represent the ground motion zonal boundaries with no fill color displaying them simply as red outlines.

Like oblong ripples in a pond, the new data showed an area of highest probability lying along the axis of my quake locations: There seems to be clear relationship among this group and seismic hazards in the area. The community of New Madrid, Missouri is squarely in the heart of the ring of highest probability along with the two 1812 events. The remaining three are very near the most potent zone.

I also chose to make a few connections to other information about this handful of events; adding Web links to the USGS story about the April 2008 earthquake, to a newspaper article for the November 1968 one, and to a drawing of the devastation in New Madrid in 1811-12. The image below offers a synthesis of all the above additions.

- George Dailey, ESRI Education Manager

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Exploring a Midwest Earthquake Zone with ArcGIS Explorer: Part II

A multi-day blog: Part 1 | Part 2 | Part 3 |
Part 4

My first task was to get these events on the globe. To do that, I needed to find out where they occurred and anything else I could discover. The best place to uncover that kind of information is via the Earthquake Hazards Program of the US Geological Survey (USGS). The data about the most recent event was easy to find as it just made news. For 1968 and 1811-12, I did a little bit of searching in the Historic Earthquake area. Once discovered, I used Notepad to build a quick table.

Next, I added the table to an ArcGIS Explorer project by using the “Import File” wizard in the Tools menu. The addition of the quakes presented an interesting linear pattern so I went back to the USGS earthquake search function and uncovered two other locations for associated New Madrid 1812 events. Using “Go to Location” in the Tool Menu, I was able to quickly add these quakes as new “Results” in my project and I included their attributes in the associated “Popup Window.”

The seeming linear nature of this quintet of events became clearer and to emphasize it, I used the “Measure” task to represent the line with the 1811 and 2008 events at the poles. I also used the “Find Place” task to put New Madrid, Missouri on the map in the path of danger. But does this straight line comparison for my sample of five hold any validity, or is it just random luck?

“Exploring a Midwest Earthquake Zone with ArcGIS Explorer: Part III” will be published April 24, 2008.

- George Dailey, ESRI Education Manager

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Exploring a Midwest Earthquake Zone with ArcGIS Explorer: Part I

A multi-day blog: Part 1 | Part 2 | Part 3 |
Part 4

Growing up in Southern Illinois near the Mississippi River, the natural hazards we faced tended to be weather or water related. But, teachers also made it clear to us that we could just as easily be threatened by rumblings from beneath our feet. As I learned, there was a series of massive earthquakes that happened in the early 1800’s in an area called the New Madrid Seismic Zone. From December 16, 1811, through February 7, 1812, a string of temblors with magnitudes estimated at 7.2 to 8.1 wracked the region. The severity of these events caused the Mississippi to “flow” backwards, change course, and result in the creation of new lakes, such as Reelfoot Lake in TN.

For a teenager, 1811 was ancient and the associated earthquakes were equally distant and improbable in the present. So imagine my surprise while at work in a clothing warehouse in downtown St. Louis on Saturday November 9, 1968, an earthquake happened. We didn’t know what it was. Major shaking of the many overhead metal clothing racks chased us outside where we had a chance to watch major buildings swaying. While not centered near the 1811-12 quakes, it was not far away, and, while only a 5.5 tremor, it seemed overwhelming in its power.

Spin forward to April 18, 2008, and the region was again visited by a potent quake. According to news stories this event, a 5.2, was the most powerful since the one I experienced 40 years earlier…

…and with these temporally separated events as backdrop, I decided to do a little geographic work with ArcGIS Explorer.

“Exploring a Midwest Earthquake Zone with ArcGIS Explorer: Part II” will be published April 23, 2008.

- George Dailey, ESRI Education Manager

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Opening a Layout in AEJEE

A lot of educators are using ArcExplorer Java Edition for Education (AEJEE), ESRI’s free, downloadable, dual platform (Win/MacOSX), lightweight GIS tool. A frequent question is how to annotate a map. This is possible only within the layout option (VIEW/LAYOUT). But if you create annotations and save the project, how do you re-open the project to see them? The trick is to open an instance of AEJEE, immediately switch to layout view, and *then* use FILE/OPEN to access the saved project. The graphic elements get stored in the project file, and reappear when opened in layout mode. (A little tinkering may be necessary to make textboxes appear exactly as originally configured.)

How does a user know to open the project in layout mode? It will help if the project creator will save the project with a name that indicates this, such as “Layout_pop05.axl” or “L_pop05.axl”. Set up a naming scheme and get used to using it.

Try the attached project file as an example.Download this file “layout.zip”, which assumes the user has AEJEE 2.3.2 installed in the default location ([harddrive]:ESRI). Store the unzipped file in a sensible place (such as ESRIAEJEEdatalessons), engage AEJEE, switch to layout mode, and open it up.

- Charlie Fitzpatrick, ESRI Education Manager

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Digging Deeper Into Population Change By County Using the 3D Analyst Extension

We have recently been examining a simple yet powerful topic that can easily be studied with a GIS—population change over time. We have been asking why population change in US counties has occurred, if current trends are radically different than past trends, and what the country will look like in another generation if current trends continue.

Analyzing population in 3D can help students understand the dimension and pattern of change over time. The ArcGIS family of products offers several excellent ways to display data in 3D. Let’s start with the 3D Analyst extension. After selecting the ArcScene function and adding your population change layer to the scene, the map can be manipulated in three dimensions. Right click on the layer name and access properties. You will notice a few new tabs, including Extrusion. Below, I ask the computer to extrude the value in the population field (called “Percent,” representing population change in percent from 1990 to 2000). This turns my county polygons into 3D blocks. I divide it by 30 so that the blocks don’t stretch up to the moon.

I also symbolized each county by Change in the symbology tab, just as you would in ArcMap. The resulting image, below, is one that the students can rotate, zoom and pan, and ask questions about as they explore.

Notice Florida and Georgia’s rapid increase in percent. How different would the data look in terms of raw number changes? The 3D extension allows you to quickly change the variable mapped to find out.

Counties losing population are “wells” underneath the surface of the Earth. I rotate to the northern Great Plains and look south from Manitoba, below.

It is my hope that the students will notice the radical difference between population change in North Dakota versus lands to the southwest. The tower in Colorado is not far from where I live—Douglas County, midway between Denver and Colorado Springs, a beautiful area but is under population growth pressure from both metropolitan areas.

- Joseph Kerski, Education Manager

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Exploring Recent Earthquakes with AEJEE

The news this weekend carried a report about a recent tectonic activity off the coast of Oregon. I decided to check this out using ArcExplorer Java Edition for Education, ESRI’s free, downloadable, dual platform (Win/MacOSX), lightweight GIS tool.

I opened up AEJEE and connected straightaway to the Geography Network. There are a couple of earthquake services there. I opened up “ESRI_Quake_Rec” and immediately saw the chaos off the Oregon coast. I zoomed in for a better look. To give an additional reference, I added “plates.shp” from the AEJEE/data/world folder, moved it to the top, set the layer as transparent, and changed the border to orange. Then I used the identify tool and looked at the biggest recent quake, a 5.2 just over one day ago.

The capacity to integrate data sources, identify specific features (even from an online service), and conduct relevant analysis of a current situation is what makes GIS a powerful tool and AEJEE a key technology for today’s students … at school, and – especially if they don’t get to use it at school – at home!

- Charlie Fitzpatrick, ESRI Education Manager

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Digging Deeper Into Population Change By County Using Research

Charlie Fitzpatrick wrote a blog on how to use AEJEE software to analyze county population change between 2000 and 2005, on:

http://blogs.esri.com/Info/blogs/gisedcom/archive/2008/03/24/exploring-pop-change-with-aejee.aspx

Using a simple county query that your students could do, he found that 1,147 counties lost population. Ask the students what it means if the nation is growing, yet 1/3 of counties are losing population. This is a much higher percentage of counties than the percentage losing population during the 1990s. The data also showed that 193 counties declined by over 10% during just those five years.

The focus of using GIS is to have students think about the spatial patterns, to get at the “whys of where.” Where are the largest declines? Why do these disparities exist? If these trends continue, what are the implications for land use, schools, and housing type?

Not two days after Charlie wrote the blog, the Population Reference Bureau published an article on this very topic, on: http://www.prb.org/Articles/2008/populationlosses.aspx.

“Population Losses Mount in U.S. Rural Areas,” stated that nearly twice the number of counties lost population during the 2000s than during the 1990s. International migration is dwarfed by migration from other parts of the country. In counties with moderate growth or loss, international migrants and their children help to stabilize the population, especially in big cities. “Domestic migrants continue to leave these areas while new immigrants come in to take their place.”

In counties rapidly declining in population, the minimal population gains through natural increase and international migration do not offset domestic emigrants seeking opportunities elsewhere. “During the 1990s, rural areas benefited from steady growth in employment, income, and tax revenue, and the rural population rebounded. But just as the strong 1990s economy created new opportunities for people to live and work in rural areas, the weak economy since 2000 may be pushing people back to metropolitan areas to find jobs with decent wages.”

This illustrates how you can effectively use current events and current research to supplement your investigation of the real-world data behind those events.

- Joseph Kerski, ESRI Education Manager

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